(19)
(11) EP 1 355 484 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
21.03.2007 Bulletin 2007/12

(43) Date of publication A2:
22.10.2003 Bulletin 2003/43

(21) Application number: 03252432.4

(22) Date of filing: 16.04.2003
(51) International Patent Classification (IPC): 
H04N 1/64(2006.01)
 H04N 1/41(2006.01)
(84) Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT RO SE SI SK TR
Designated Extension States:
AL LT LV MK

(30) Priority: 17.04.2002 JP 2002114773
27.11.2002 JP 2002344574
07.03.2003 JP 2003061865

(71) Applicant: CANON KABUSHIKI KAISHA
Tokyo (JP)

(72) Inventors:
  • Tanaka, Tetsuomi, c/o Canon Kabushiki Kaisha
    Tokyo (JP)
  • Yamazaki, Takeshi, c/o Canon Kabushiki Kaisha
    Tokyo (JP)

(74) Representative: Beresford, Keith Denis Lewis et al
BERESFORD & Co. 16 High Holborn
London WC1V 6BX
London WC1V 6BX (GB)

   


(54) Image compression method and apparatus, and image coding method and apparatus


(57) There are provided an image coding method and apparatus and image compression method and apparatus which can properly compress a color document image with a high compression efficiency. First of all, a color reduction processing unit (102) converts each pixel of a color document image into an index assigned in correspondence with a color value, and generates color information (103) containing the number of pixels for each indexed color and an index color image (104). A color information sort unit (105) and the like determine, for example, a color value corresponding to an index of the maximum number of pixels as a background color. An order determination unit (113) determines an order. A binary image generation compression unit (109) generates a partial binary image for each index and compresses the binary image according to the order. A data integrating unit (111) generates compressed image (112) by integrating background data (108) and the compressed data of the partial binary image.







Search report